The present invention relates to a semiconductor device, especially to a semiconductor device provided with a filter circuit employed in a radio frequency integrated circuit (RFIC), for example.
In an RFIC (semiconductor device) implemented in wireless communication devices, such as a mobile-phone and a wireless LAN (Local Area Network), a filter circuit for removing an unnecessary out-of-band signal is provided in each of a receiving unit for downconverting a reception RF signal received with an antenna to a reception baseband signal, and a transmitting unit for upconverting a transmission baseband signal to a transmission RF signal. Such a filter circuit is generally configured with the use of an inductor, a capacitor, and a resistive element (refer to Patent Literature 1, for example).
For example, when an LC circuit configured with an inductor and a capacitor coupled in parallel is employed as the filter circuit, input impedance of the filter circuit becomes maximum at a resonance frequency of the LC circuit. Therefore, the filter circuit functions as a kind of band-pass filter which passes a frequency in the neighborhood of the resonance frequency and attenuates a frequency distant from the resonance frequency.
(Patent Literature 1) U.S. Pat. No. 5,095,285